Cooler tubes for rotary kiln

ABSTRACT

An improved cooler tube construction for rotary kilns is disclosed which includes a conical internal surface located at the inlet end of each cooler tube. This conical surface acts to prevent back-spill and to advance material through the cooler tube.

United States Patent [191 Gommesen 1 May 28, 1974 [541 COOLER TUBES FORROTARY KILN 2,904,522 9/1959 Bruff 432/117 5 l H 3,279,775 l0/l966Ronbal [7 1 C n 3,372,915 3/1968 Jensen Denmark 3,556,495 H1971 Jensen[73] Assignee: S. L. Smith & C0., Cresskill, N,J 3,643,933 2/1972McDonald 432/80 [22] Filed: Sept. 13, 1972 Primary Examiner-John J.Camby [21] Appl' 9 Assistant Examiner-Henry C. Yuen Attorney, Agent, orFirm-Pennie & Edmonds [30] Foreign Application Priority Data Sept. 20,1971 Great Britain 43766/71 [52] U.S. Cl 432/80, 432/1 1634/1354 ABSTR C[51] Int. Cl. F27b 7/20 [58] Field of Search 432/103-106, An improvedcooler tube construction for rotary kilns 432/80, 83, 115, 117, 26, 45;34/134, 135, is disclosed which includes a conical internal surface 109,127; 165/88 located at the inlet end of each cooler tube. This conicalsurface acts to prevent back-spill and to advance [56] 9 ReferencesCited materialthrough the cooler tube. UNITED STATES PATENTS 828,5558/1906 Krottmaurer 432/117 3 Claims, 4 Drawing Figures l COOLER TUBESFOR ROTARY KILN BACKGROUND OF THE INVENTION t openings and communicatingchutes into each cooler tube as it passes through the lowermost point ofits path of travel. Air is drawn or blown through the cooler tubes in adirection countercurrent to the hot material so as to cool it andsubsequently enters the kiln through the outlet openings through whichthe hot material passes to the cooler tubes via the chutes. Thispreheated air is then utilized to support combustion within the kiln.

The kiln shell in rotary kilns of the type disclosed herein is generallymounted such that its axis of rotation is inclined upward in thedirection opposite to the direction of material movement or flow withinthe kiln body. In one construction the cooler tubes extend alongside thekiln shell and are inclined upward in the direction in which materialflows through the cooler tubes (i.e. in a direction opposite to thedirection of material flow through the kiln shell.) Such cooler tubesare commonly known as uphill cooler tubes. In another construction, thecooler tubes extend away from the outlet end of the kiln shell and areinclined downward in the direction in which material flows through thecooler tubes (i.e., in the same direction as material flow through thekiln shell) in which case the cooler tubes extend-away from the outletend of the kiln shell. The latter cooler tubes are commonly known asdown-hill cooler tubes. In either construction the cooler tubes may beparallel or inclined at an angle to the axis of the kiln. Commonly thecooler tubes contain scoops, chains or other devices by which thematerial in them is urged towards their outlet ends, particularly withthose constructions equipped with up-hill cooler tubes.

With rotary kiln constructions of the type described, there is often atendency for some of the hot material entering each cooler tube when itis in its lower most position below the axis of the kiln to return tothe kiln again when the cooler tube reaches its uppermost position abovethe kiln axis since, when in this latter position, the outlets of thecommunicating chutes are of course above their inlets. This return orbackspill of material is very undesirable because it not only reducesoutput but also hinders the free passage of preheated air into the kiln.

Several kiln constructions have been proposed to eliminate or diminishback-spill. For relatively heavy, dustless or large particle materialthe problem of backspill has been to some extent overcome by providingoblique passages from the kiln to the cooler tubes rather than radialcommunicating chutes. In one construction the oblique passage iscombined with a special form of the inlet end of the cooler tube. Withthis construction the part of the cooler tube at its inlet end which isopposite the mouth of the communicating chute is constituted by a partof the cylindrical wall of the tube and the part that'is-nearer the kilnshell is formed as a section of a cylinder the axis of which is soinclined to that of thetube as to provide a surface down which materialin the'tube' may slide away from the outlet of the chute when the tubeis above the kiln axis.

The present invention is specifically concerned with a new and improvedconstruction of the inlet end of a cooler tube to substantiallyeliminate back-spill even when the charge in each cooler tube is largerthan normal.

SUMMARY OF THE INVENTION According to theinvention the cooler tube andcommunicating chute are connected together in substantially tangentialrelationship and the end wall of each cooler tube adjacent thecommunicating chute includes a conical surface concave to the interiorof the cooler tube with its apex at or near the junction point of thecooler tube and communicating chute. The conical surface is oriented insuch a way that it advances incomming material away from the opening inthe communicating chute. The conical surface also acts to preventback-spill of material into the chute.

To further guard against back-spill, each chute of a kiln constructedaccording to this invention may be comprised of two or more straightpipes. At least two of these pipes are disposed in angular relationshipwith respect to each other. Thereby, a knee bend is formed in each chutewhich advantageously acts to trap backspilling material inadvertentlyentering the chute upon rotation of the kiln.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTIONWith reference to FIG. I a rotary kiln 1 having a refractory lining 3 isshown for burning of a charge 2 of raw material (eg cement raw material)to clinker. At its outlet or lower end the kiln has a number of outletopenings 4 which communicate through chutes 5 with a correspondingnumber of cooler tubes 6 mounted with their axes substantially parallelto the axis of the kiln and arranged equiangularly around the kiln shellin a planetary fashion.

Each cooler tube comprises a cylindrical tube having an outlet 7 in oneend of the tube and an inlet opening registering with the correspondingcommunicating chute 5. In the construction shown, the communicatingchute 5 is comprised of two or more straight pipes ll, 12 and 13 whichare joined together (e.g. by welding). Straight pipes 11 and 12 areconnected together in angular relationship to thereby form a knee bend14 pointing in the direction of rotation of the cooler tube indicated bythe arrow in FIGS. 2 and 3. The cooled material discharged from thecooler tubes 6 is collected in a hopper 8 from which it is removed byconventional means well known in the art.

The inlet end of each cooler tube is closed by a conical surface 9concave to the interior of the tube and having its apex 10 at or nearthe junction point of the communicating chute 5 and the cooler tube.

During operation material in the kiln rests substantially on one side ofa central plane extending diametrically through the kiln. Usually,material is lifted within the kiln shell during rotation of same to forma cushion of material located substantially on one side of such adiametrical plane which is vertically oriented. During rotation thematerial processed in the kiln moves from the inlet end to the outletend of the kiln shell where it flows into the cooler tubes through thecommunicating chutes. The material will start to spill over into thecommunicating chutes as they pass through the lowermost point in theircircular path and slide gently through the communicating chute onto thecylindrical surface of the cooler tube.

As the tube moves upwards in its circular path, the material slides onthe cylindrical surface of the cooler tube and is advanced in adirection away from the inlet end of the cooler tube by the conicalsurface 9 which acts to push the material forward in the cooler tube.

When the cooler tube has passsed its uppermost position, the cushion ofmaterial in the cooler tube, despite its general forward movement, maystart to slide backwards because at this point the transporting effectof the conical surface is diminished. However, the tongue of the cushionof material will under normal circunstances be kept away from theopening in the communicating chute because of the barrier formed by theconical surface 9. Thus the conical surface acts to prevent back-spill.

Under certain conditions the charge in the cooler tube may be very high.For example it may be filled to 50 percent or more of its capacity. Someof the material may under such conditions reach the opening during thefirst of downward movement of the cooler tube, i.e. between itsuppermost position and its position generally defined by a horizontalplane through the axis of the kiln. Any material which does then passinto the communicating chute will be trapped by the knee bend formed bythe pipe sections 11 and 12 and thus prevented from reentering the kilnshell.

I claim:

1. In a rotary kiln having a plurality of cooler tubes mounted inplanetary fashion around the outlet end of the kiln with the inlet endof each tube connected to the outlet end of the kiln by a communicatingchute substantially tangentially disposed with respect to the coolertube, the improvement which comprises said chute having a first pipecommunicating with the outlet end of the kiln, and a second pipe incommunicating angular relationship with the first pipe such thatbackspilling material is trapped and is prevented from reentering thekiln, and a conical wall forms at least a part of the inlet end of eachcooler tube, said conical wall having a conical surface concave to thecooler tube, said conical surface being oriented so as to cooperate withthe tangentially mounted communicating chute to advance materialentering the cooler tube away from the opening in the communicatingchute.

2. The improvement according to claim 1 wherein said conical surface hasits apex approximately at the junction of the chute and the cooler tubeto advance material entering the cooler tube away from the opening inthe communicating chute in an improved manner.

3. The improvement according to claim 2 wherein said first and secondpipes of said communicating chute are connected together to form aknee-bend pointing in the direction of rotation of the cooler tube.

1x33 UNITED s'mrus im'lm'l. OFFLCE r I O .L I CX'JR J. .U. .lL/x'flu O1"CORRLCTJON Patent No.; 3731731211- v v D t d May- 28, 1974 InventorCs)Hans Gommseri It is certified that error appears in the above iden I Atified t and that said Letters Patent are hereby corrected as shovmbelow ant 1. Under "Assignee" "S. L. Smith & Co. should read F. L Smidth& Co.-.

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL 'DANN Attesting Officer Commissioner ofPatents

1. In a rotary kiln having a plurality of cooler tubes mounted inplanetary fashion around the outlet end of the kiln with the inlet endof each tube connected to the outlet end of the kiln by a communicatingchute substantially tangentially disposed with respect to the coolertube, the improvement which comprises said chute having a first pipecommunicating with the outlet end of the kiln, and a second pipe incommunicating angular relationship with the first pipe such thatback-spilling material is trapped and is prevented from reentering thekiln, and a conical wall forms at least a part of the inlet end of eachcooler tube, said conical wall having a conical surface concave to thecooler tube, said conical surface being oriented so as to cooperate withthe tangentially mounted communicating chute to advance materialentering the cooler tube away from the opening in the communicatingchute.
 2. The improvement according to claim 1 wherein said conicalsurface has its apex approximately at the junction of the chute and thecooler tube to advance material entering the cooler tube away from theopening in the communicating chute in an improved manner.
 3. Theimprovement according to claim 2 wherein said first and second pipes ofsaid communicating chute are connected together to form a knee-bendpointing in the direction of rotation of the cooler tube.